Zirconia coating stabilized super-iron alkaline cathodes

A low-level zirconia coating significantly stabilizes high energy alkaline super-iron cathodes, and improves the energy storage capacity of super-iron batteries. Zirconia coating is derived from ZrCl4 in an organic medium through the conversion of ZrCl4 to ZrO2. In alkaline battery system, ZrO2 provides an intact shield for the cathode materials and the hydroxide shuttle through the coating sustains alkaline cathode redox chemistry. Most super-iron cathodes are solid-state stable, such as K2FeO4 and Cs2FeO4, but tend to be passivated in alkaline electrolyte due to the formation of Fe(III) over layer. Zirconia coating effectively enhances the stability of these super-iron cathodes. However, for solid-state unstable super-iron cathode (e.g. BaFeO4), only a little stabilization effect of zirconia coating is observed.